Metastatic melanoma is one of the fastest growing cancers, causing more than 8,650 deaths in 2009 alone, and this number is projected to increase over time. Models for the study of melanoma have multiple limitations, including the inability of most transgenic systems to accurately reproduce complex disease phenotypes such as cancer, and the inability of human embryonic stem (hES) and human induced pluripotent stem (hiPS) cell technology to reproduce the host microenvironments. It has been shown, however, that aggressive melanoma cells up-regulate a subset of neural crest (NC) cell guidance and differentiation markers as well as being a NC cell-derived cancer. We hypothesize that an in vivo platform for the study of melanoma development, invasion, and metastasis can be created using human NC cell chimeras. There are two specific goals of this study: 1) to optimize the incorporation of hES and hiPS cell-derived NC cells into a murine system, and 2) to model human melanoma development and metastasis in vivo. These chimeras will be created by in utero injections of hES or hiPS cell-derived NC cells into the developing mouse embryo at embryonic day 8.5 (E8.5). Human NC donor cells will be labeled with the eGFP marker and injected embryos will be analyzed during gestation and post-natally to localize the injected cells and establish methods optimizing their survival and colonization, such as the over-expression of NC cell survival genes via lentiviral transfection. We will then utilize this chimeric system to over-express common genes with known roles in melanoma, and inject these NC cells in utero at E8.5 to model melanoma initiation and development in vivo in a murine model system. Additionally, we will promote tumor formation of the hES or hiPS cell-derived NC cells after subcutaneous injection into an immune-compromised mouse, and the tumor cells formed can be cultured and re-injected at E8.5 into the developing mouse embryo to study tumor migration and metastasis over the developmental period. Overall, we propose to bridge the studies of embryonic development with cancer development, focusing on melanoma. We will analyze the progression of melanoma using hES/hiPS cell technology coupled with in vivo murine modeling. This novel system will not only bridge the knowledge of embryonic development and cancer biology, but will provide an in vivo model of melanoma to be used for testing potential therapeutic agents.